Wind power has emerged as a highly competitive form of renewable energy. Wind power is frequently produced by large generators comprising a vertical structure on top of which is located at least one horizontal axis wind turbine that includes one, two, three or multiple rotor blades. Wind power generators or simply ‘aerogenerators’ are designed to exploit wind energy existing at a particular location and therefore vary in height, control system, number of blades, blade orientation, shape and materials. Descriptions of the methods and apparatus for manufacturing aerogenerator blades may be found in the prior art, for instance, in the Handbook of Wind Energy, Burton el at., John Wiley & Sons Ltd, 2001, Chapter 7.1., as well as in US Patent Applications Publication No. 2004/0253114A1 and 2007/0251090A1. As mentioned in US2004/0253114A1, it may be difficult and/or time-consuming to form some components of the rotor blade shells, for example, spar caps, core material, and/or root section supports, such that they will both sufficiently support the rotor blade shell and be formed into the predetermined aerodynamic shape, for example, because of the size of the layers, local variations in resin content, local variations in a curvature of the layers, and/or local variations in strains exerted on the shell during fabrication thereof. One possible approach for such problem, as described in US2004/0253114A1, is laying up pultrusions, i.e. a mix of fibers and matrix that is cured after formation, with wood fibers in a mould and laminating them together.